SUMMARY PROJECT This collaborative project, between McLean Hospital, Harvard Medical School, USA and Cape Town University, South Africa, proposes to investigate the biological mechanisms underlying effects of maternal stress on infant development. Prospective, longitudinal, mother-child cohort studies have found that children exposed to maternal psychological stress, depression, or anxiety during the prenatal period have higher risk for behavioral and emotional problems later in life, including increased fearfulness, anxiety, and depression. We propose to examine RNA-mediated epigenetic factors in this proposal. We recently found that adults with comorbid PTSD and/or Depression (PTSD/MDD) have reduced expression of the DICER1 gene, which plays a central role in stress-related pathways by controlling ncRNA expression. Additional new work from our group has shown differential expression of a long non-coding RNA (lncRNA), GAS5, which directly regulates glucocorticoid receptor sensitivity, in recently traumatized adults as a predictor of later PTSD development. lncRNAs regulate expression of more than half of all protein-coding genes post-transcriptionally in the body. This study will extend our adult PTSD findings of DICER1, GAS5 and other lncRNA pathways, to elucidate mechanisms underlying transmission of risk across generations using an integrative developmental model in the Drakenstein mother/infant cohort. In aim 1, we will focus on in utero developmental RNA profiles. We will examine lncRNA and lncRNA-mediated epigenetic effects at birth, in infants exposed in utero to maternal PTSD/MDD by investigating RNAs that are altered in both mothers with PTSD/MDD and their infants in the Drakenstein mother/infant cohort (N=450). In aim 2, we will focus on early life developmental RNA profiles. We will examine longitudinal stability of lncRNA-mediated epigenetic factors associated with exposure to maternal PTSD/MDD at birth and at age 2 and 5 years. We will identify lncRNA-based factors that are persistently altered in exposed infants at birth across age 5 to elucidate the effects of maternal stress during early life development, which may prelude to manifestation of negative outcomes later in life. In aim 3, we will focus on early life RNA profiles and subsequent behavioral-developmental outcomes. We will identify the effects of RNA profiles at birth, age 2 and 5 years on behavioral and developmental measures at ages 2, 3.5 and 5 years. In utero and environmentally induced changes in expression levels of RNA-mediated epigenetic factors may predict development of behavioral and emotional problems. Through each of these aims, the proposal will build research capacity through training, site visits, collaborative data analyses, publications, and presentations. Through collaboration between the low- and middle-income country (LMIC) and upper- and middle-income country (UMIC) institutions we will lay foundation via infrastructure and collection of unique phenotypes and RNA-sequencing data for future studies of this unique mother-child cohort in the LMIC, advancing our understanding of risk and child development.